And as he has, a nagging question has dogged White House deliberations: What will be the impact on relations in the region – and on vital American interests – if the over-arching perception among leaders is of the US abandoning a longtime friend?

As the US looks more and more like it is “throwing in the towel” on Mr. Mubarak, one unwanted result could be a building mistrust between the US and countries it relies on for cooperation on issues ranging from international terrorism and the flow of energy to the Arab-Israeli peace process and the containment of Iran, experts in the region say.

“Other authoritarian governments will view with deep unease how quickly the US government appears to have abandoned its closest friend in the region,” says David Schenker, director of the Arab politics program at the Washington Institute for Near East Policy. “We’ll see the effects of this for years to come.”

The depth of the administration’s concern could be read between the lines of a White House statement Thursday summarizing Mr. Obama’s telephone conversation a day earlier with Yemen’s President Ali Abdullah Saleh. Obama called “to welcome the significant reform measures” President Saleh announced Wednesday, including a commitment not to run for reelection in 2013. Obama also stressed that Saleh “now needs to follow up his pledge with concrete actions.”

And by the way, the readout said, the US president also told the Yemeni leader that “it is imperative that Yemen take forceful action against Al Qaeda in the Arabian Peninsula (AQAP) to protect innocent lives in Yemen as well as abroad.”

In other words, heed your people’s demands, but don’t forget our interests while you’re at it.

US principles vs. interests

It’s a tough, perhaps even unwinnable tug-of-war between principles and interests, some US foreign policy experts say.

“We have a stark dilemma in our own minds between … how long you stand by an old friend, and keeping Egypt on our side in our regional strategy,” says Charles Freeman, a longtime US diplomat and former ambassador to Saudi Arabia. “It’s really an irreconcilable contradiction.”

The Obama administration has so far followed a bifurcated approach of supporting both the popular uprisings sweeping across the region and friendly regimes moving to implement reforms.

“I think we’ll see the dual track for a while,” says Mr. Schenker. “The US is caught between these two competing and in some ways contradictory priorities” for popular expression and political change on the one hand, and regional stability on the other, he says. And no matter who replaces Mubarak in Egypt, he adds, the new leaders are likely to remember the US actions.

“What if Mubarak goes but a part of the regime aligned with his regime and the military wins?” Schenker says. “They’re going to be cautious about the US. And if it truly is a more representative government,” he adds, “they simply aren’t going to be as supportive of US policies as” Mubarak was.

The US may support the people’s aspirations, but at the same time the reality is that diplomacy is primarily a government-to-government exercise, others note – and America’s friends won’t soon forget US actions in the upheaval of 2011, they say.

'US power would crumble'

“Our soothsayers should also understand that when our other Arab friends watch us help remove Mubarak from power by not backing him, they'll believe that they'll be next on the list if they run into trouble,” wrote Leslie Gelb, a member of the Council on Foreign Relations, in a recent Daily Beast post. “US power would crumble in the region.”

Despite such dire predictions, others say the administration is making the best it can of a bad situation. “The administration has been doing a skillful job of obfuscating this issue by not making a clear choice,” says Ambassador Freeman.

And Schenker gives the administration good marks for focusing on the established military-to-military relations in the case of Egypt as a way of maintaining good bilateral relations no matter the political makeup of the next government.

“I see the US trying to further leverage the good military-to-military relations we have, and that’s a positive move,” he says. “The problem is that while we can count on the Egyptian military to continue to want access to the US military for its officer corps and to want access to US weapons,” he adds, “other countries don’t have that same close relationship.”

One early conclusion among some regional experts is that perhaps the starkest legacy of an era of mistrust will be diminished American influence. “The willingness of local leaders to become as dependent on the US as Hosni Mubarak was is likely to be repudiated in the future,” Freeman says. “My guess is we are entering a new era of greatly diminished American prestige and clout.”